Chroma
Luma
Internal Modules
61
SPRUHI7A – December 2012 – Revised June 2016
Copyright © 2012–2016, Texas Instruments Incorporated
High-Definition Video Processing Subsystem (HDVPSS)
1.2
Internal Modules
This section describes the internal modules of the high-definition video processing subsystem (HDVPSS).
1.2.1 Chroma Up-Sampler (CHR_US)
The chroma up-sampler (chr_us) module is used to convert from YCbCr 4:2:0 data format input to YCbCr
4:2:2 format output.
1.2.1.1
Features
•
Supports both interlaced and progressive inputs
•
4-tap interpolation filtering
•
Filter coefficients are all programmable
•
Four sets of coefficients (each set has four coefficients) corresponding to anchor pixels and
interpolated pixels of top field and bottom field
•
For progressive inputs, the coefficients corresponding to top and bottom field must be identical
•
Each coefficient is 14 bit (4.10 format)
•
Default filter coefficients are based on Catmull-Rom algorithm
•
Capable of removing the half pel vertical offset so all chroma samples are on-grid. This step ensures
that the output does not suffer from any kind of rainbow effect due to chroma-upsampling.
•
Provides a 10-bit interface in both directions: 10-bit input and 10-bit output
•
Support bypass mode for 4:2:2 input
1.2.1.2
Functional Description
The YUV420 input to Chroma Upsampler module must be in the format shown in
, in which the
chroma sample lies in the left column of a 2x2 pixel block with half pel vertical shift.
Figure 1-16. 4:2:0 YCrCb Color Space with Chroma Left-aligned
The upsampling is performed by an interpolation filter which uses Catmull-Rom algorithm. The Catmull-
Rom Filter is based on four anchor pixels representing a four tap filter. The general 4-tap filter Catmull-
Rom filter is defined in
.